For electrophotographic processes or electrostatic recording process, developers that visualize electrostatic images or electrostatic latent images may be classified into two-component developers and one-component developers. Two-component developers are composed of toner and carrier particles; whereas one-component developers are substantially composed of only toner. That is, one-component developers do not use carrier particles. One-component developers may be further classified into magnetic developers and nonmagnetic developers, in which magnetic developers contain a magnetic component while nonmagnetic developers do not. In addition, fluiding agents may be added to nonmagnetic one-component developers in order to improve the fluidity of the toner. Examples of fluiding agents include, but are not limited to, colloidal silica and the like.
In general, toners contain colored particles, which may be obtained by dispersing a pigment such as carbon black or other additives in latex. These toner may be prepared using a grinding method (sometimes also referred to as a pulverizing method) or a polymerizing method. In the grinding method, a synthesized resin, a colorant and optionally other additives are dissolved and mixed together. The resulting mixture is ground. The particles resulting from the grinding or pulverization are classified or sorted in order to obtain particles having a desired diameter. In the polymerizing method, a polymerizable monomer, a colorant, a polymerization initiator and optionally other additives, such as, for example, a crosslinking agent or an antistatic agent, are homogeneously dissolved together or are dispersed to form a polymerizable monomer composition. The polymerizable monomer composition may be dispersed with an agitator in an aqueous dispersion medium containing a dispersion stabilizer so as to form droplet particles of the composition. The temperature of the composition may be increased and a suspension-polymerization process may be performed on the composition to obtain color polymerization particles having the desired particle diameters, that is, the desired polymerization toner.
Toner for developing an electrostatic latent image described above may contain impurities, which may be the source of an unpleasant odor. For example, aromatic impurities having low molecular weights may generate an unpleasant odor when the toner is used or when a packaged toner is open.
Toner may be fixed to a surface of a medium (e.g., a sheet of paper) through the use of a fixing method. For example, fixing methods include methods such as a compression fixing method, a heat fixing method, or a combination thereof. Examples of the heat fixing method include an oven fixing method, a flash fixing method, and a heating roller fixing method. The heating roller fixing method is widely used in electrophotographic copiers and printers. When a toner image on a medium is fused onto a surface of a the medium by using the heating roller fixing method, the toner image can be quickly fixed with high thermal efficiency. In particular, the heating roller fixing method is very useful for high-speed copying and printing.
Since the heating roller fixing method includes heating of the toner, small amounts of materials contained in the toner may also be discharged into the surrounding atmosphere resulting in an unpleasant odor. With the reductions in the sizes of copiers and printers, they use in an office or home setting has become more prevalent, increasing the likelihood of a user being exposed to the unpleasant odor generated from toner. The human sense of smell may be as low as 0.1 ppm or less.
The unpleasant odor induced from toner may be reduced by decreasing the impurities, for example, contained in the binder resin. For example, the unpleasant odor may be reduced by decreasing the monomer residue in the binder resin of the toner. The oxidation product of benzaldehyde contained in toner has also been reported as a source of an unpleasant odor. Accordingly, there have been many efforts made in an attempt to reduce the amount of benzaldehyde present in toner. In addition, much research has been conducted into the feasibility of adding to toner a material that reacts with or adsorbs the unpleasant odor. For example, these materials include but are not limited to an alkyl betaine compound, catechin, and metal phthalocyanine. However, there is still a need to develop toner that generates less of an unpleasant odor while maintaining the other desirable properties of the toner.